If an advertiser lowers a custom bid, Pinterest may still surpass that bid value in the next auction.

This statement is false. When an advertiser sets a custom bid, Pinterest's auction system will not exceed that bid value. The custom bid acts as a cap, ensuring that the advertiser never pays more than their specified maximum for an action (e.g., a click or impression). While the actual cost per action (CPA) may be lower than the custom bid, it will never be higher. This mechanism provides advertisers with control over their spending and helps manage campaign budgets effectively.